Many studies
have found associations between parent and child characteristics.
Although genetic models partition phenotypic variance into
genetic and environmental influences, parents' genetic and
environmental influences are confounded when children are
raised by their biological parents. Kerr et al. (2013) separated
mothers' genetic and environmental influences by analyzing
associations of depressive and antisocial characteristics
of birth mothers' (BM) and adoptive mothers (AM) with Internalizing
and Externalizing scores obtained from CBCL/1½-5 forms
completed separately by AM and by adoptive fathers (AF) when
the children were 18, 27, and 54 months old. The children
were all born in the U.S. and adopted by families living in
the U.S. After controlling for many variables, including obstetric
risk factors, mothers' prenatal depressive symptoms, and postnatal
adoptive family contact with BM, Kerr et al found that BM
lifetime depressive symptoms assessed via diagnostic interviews
(surprisingly) predicted CBCL/1½-5 Externalizing scores,
whereas BM antisocial behavior (surprisingly) predicted CBCL/1½-5
Internalizing scores. Moreover, AM depressive symptoms and
antisocial behavior both predicted both CBCL/1½-5 Internalizing
and Externalizing scores! Several AM predictive paths but
not BM predictive paths were replicated in AF CBCL/1½-5
ratings. The replications in AF ratings indicated that the
AM predictive paths were not artifacts of biases in AM CBCL/1½-5
ratings. However, the failure to replicate BM mothers' predictive
paths suggests that AM ratings but not AF ratings captured
aspects of children's problems not captured by AF ratings.
The authors concluded that "depressive and antisocial
dimensions of maternal psychopathology confer independent
risks for . . . early childhood behavior outcomes" and
that "This is consistent with recent factor-analytic,
epidemiologic, and genetic studies that all point to two distinct,
heritable liabilities underlying most comorbidity among psychiatric
syndromes: an internalizing and externalizing factor"
(p. 731).